1. Field of the Invention
The present invention relates generally to methods for making refrigerant tubes for heat exchangers. More particularly, the present invention relates to a method for making a refrigerant tube for a heat exchanger wherein the tube is formed from identical members having asymmetric sides.
2. Disclosure Information
Heat exchangers employ a wide variety of tube geometries depending upon the heat transfer characteristics needed to be achieved. For example, U.S. Pat. No. 5,381,600 discloses a condenser for an automotive vehicle using round tubes having an internal surface with corrugation-like teeth formed thereon. Other heat exchanger designs use different types of tubes. A second example can be found in air conditioning system condensers of the parallel flow type. In this type of condenser, substantially flat refrigerant tubes are used. These tubes must withstand high pressure gaseous refrigerant which flows through them and still achieve high heat transfer characteristics. As is well known, these flat tubes have a plurality of discrete flow paths formed therein. The flow paths can be formed by inserting an undulating metal insert into the tube and brazing the insert into place. The flow paths can also be formed by forming walls in the tube during an extrusion process.
U.S. Pat. No. 5,553,377 teaches a method for making refrigerant tubes for use in condensers. The tubes in the '377 patent are formed from two members, a bottom member having a plurality of walls along the longitudinal length of the tube and a top member which acts as a "lid" or cover. The top member is brazed to the bottom member to form the tube. However, during fabrication of this type of tube, the top member must be held securely in place to prevent it from sliding relative to the bottom member. The top and bottom members of the tube are substantially different in shape, requiring further labor and expense in fabricating this tube. It would be advantageous to achieve the beneficial effects of a generally flat tube formed by joining two members together without incurring the substantial labor and cost associated with multiple designs.
It is an object of the present invention to provide a method for making a refrigerant tube which is less expensive to manufacture by employing identical tube members joined together to form the tube.
It is a further object of the present invention to provide a tube which is formed from two members which lock together during the fabrication process to prevent relative movement between the members during brazing.